EFFECTS OF HEAT TREATMENT ON THE MECHANICAL PROPERTIES AND CORROSION BEHAVIOUR OF 5SP ROLLED STEEL

Abstract

Investigations were carried out to study critically the effect of heat- treatment on the mechanical properties and corrosion behaviour of 5sp rolled steel products. The steel was heated to a temperature of 830°C to completely austenize it and water quenched, it was reheated to the ferrite-austenite two phase region at a temperature of 745°C below the effective AC3 point. The steel was then rapidly quenched in water and tempered at a temperature of 480°C to provide an alloy containing strong, tough lath martensite (fibres) in a ductile soft ferrite matrix. The corrosion behaviour of the steel in marine medium (NaCI) was also studied by weight loss measurement. The weight loss is between 0.029-0.119 for the as-rolled steel and 0.01g-0.0139 for the heat treated specimens. The steel developed has excellent combination of tensile strength, impact strength, ductility and corrosion resistance which is very attractive for structural use.